“If the ocean floor had a nervous system, it might look something like this: thousands of miles of fiber-optic cables connected to sensors set atop the fault lines where Japan’s earthquakes begin. Completed in June, this system aims to stave off devastation like that of 2011—when a relentless six-minute-long temblor was followed by a 130-foot tsunami that reached speeds of 435 miles per hour and pounded cities into rubble. Delayed alerts gave some communities less than 10 minutes to evacuate and only warned of much smaller waves, based on inaccurate earthquake readings. Nearly 20,000 people died, with thousands more injured or missing…

With the final N-net link set up this June, the complete system increases warning times by 20 seconds for earthquakes and a full 20 minutes for tsunamis—enough time to divert incoming flights and close sea gates in busy ports.”

From Scientific American.